Butadiene Content Research Articles

Effect of styrene–butadiene–styrene triblock copolymer structure on the rheological properties of high content SBS polymer modified asphalts

Styrene-butadiene-styrene triblock copolymer (SBS) is a thermoplastic elastomer synthesized through the anionic polymerization. The effects of SBS structure including diblock content, molecular weight and styrene content on the properties of high content SBS polymer modified asphalts (HCPMA) with 8wt% were studied. The structure of SBS was characterized by the Size Exclusion Chromatography. The rheological properties of HCPMA were analyzed by performance grading, linear amplitude sweep and zero shear viscosity. The results show that the increasing diblock content decreases the melt viscosity, and improves the workability and the thermal-cracking resistance of HCPMA. However, it reduces the high-temperature performance and fatigue resistance. Higher molecular weight of SBS improves the high-temperature properties and fatigue resistance of HCPMA, but worsens the workability and hot-storage stability. Asphalts modified by SBS with a higher styrene content show better workability and high-temperature properties, while a higher butadiene content in SBS shows better hot-storage stability and thermal-cracking resistance of HCPMA. When the styrene content of SBS is 30%, the binder represents the best fatigue resistance. The results also show that rheological tests characterize HCPMA more precisely than the conventional methods.

Facile preparation of high-performance and multifunctional PVC-based nanocomposites with segregated structure achieved by volume repulsion and toughening effects of ABS

A facile and industrially feasible approach for preparation of polyvinyl chloride (PVC)/conductive carbon black (CCB) nanocomposites with good electrical conductivity, thermal conductivity, flame retardant property and toughness has been developed in this work. Specifically, acrylonitrile–butadienestyrene elastomer containing 67 wt% butadiene content (ABS) is chosen as volume exclusion phase and toughening phase for constructing PVC/CCB nanocomposites with segregated filler network structure and sea-island phase structure. Benefiting from more intact and denser filler network provided by segregated structure, the resultant PVC/ABS/CCB nanocomposites have exhibited higher electrical and thermal conductivity than those of PVC/CCB nanocomposites. Benefiting from high elasticity of polybutadiene rubber and molecular interface compatibility between PVC and acrylonitrile-containing shell of ABS, the resultant PVC/ABS/CCB nanocomposites have also exhibited excellent toughness. In a word, the as-fabricated PVC/ABS/CCB nanocomposites have advantages of low cost, simple preparation, high mechanical property and versatile functions, endowing them great practical value.

Ethylene‐Butadiene Copolymerization and Ethylene‐1‐Hexene‐Butadiene Terpolymerization with a MgCl2‐Supported Ziegler‐Natta Catalyst: Polymer Structure and Active Centers

AbstractIn this work, systematic studies on ethylene/butadiene copolymerization and ethylene/1‐hexene/butadiene terpolymerization with a TiCl4/ID/MgCl2(ID=diester) type Z−N catalyst were conducted in slurry process under 1 atm ethylene pressure, and the effects of initial butadiene concentration ([Bd]0) on polymerization activity, copolymer structure, active center number ([C*]/[Ti]) and active center distribution were studied. Activity of the co‐ and terpolymerization was evidently lowered by raising [Bd]0. The butadiene incorporations were highlytrans‐1,4 regio /stereoselective. Addition of 1‐hexene caused increase in polymerization activity, and 1‐hexene incorporation rate was reduced by raising [Bd]0. Both the copolymer and terpolymer were composed of two fractions with high and low butadiene content, respectively. The fraction with low butadiene content (insoluble in boilingn‐heptane) accounted for more than 85 % of the copolymer and more than 70 % of the terpolymer. [C*]/[Ti] was determined by quench‐labeling the propagation chains by thiophene‐2‐carbonyl chloride. [C*]/[Ti] first increase to about 80 % and then decreased with increase of [Bd]0. A part of active centers was deactivated by butadiene when [Bd]0was higher than 0.2 mol/L. Addition of 1‐hexene slightly increased [C*]/[Ti] ratio. By using supported Z−N catalysts, it is feasible to synthesize ethylene‐butadiene copolymer and ethylene‐1‐hexene‐butadiene terpolymer with relatively low butadiene content (≤1 mol %) at acceptable catalyst efficiency (about 50 % of the polymerization systems without butadiene).

Well-Tailored Dynamic Liquid Crystal Networks with Anionically Polymerized Styrene-Butadiene Rubbers toward Modulating Shape Memory and Self-Healing Capacity

Well-tailored construction of liquid crystal networks (LCNs) with simultaneous molecular mobility and mechanical enhancement is desirable. Since the properties of polymeric materials are largely a result of the molecular compositions of polymer chains, in the present work, we demonstrate the tuning compositional synthesis of anionically polymerized random styrene-butadiene rubbers (r-SBRs) with well-controlled 75 wt % butadiene (Bd) contents that offer molecular mobility. Microstructural 1,2-olefins of 51.5–64.0 mol % were designed to attach 50 mol % SiH-terminated mesogenic moieties (M) along Bd units using hydrosilylation. As mechanical strength usually conflicts with high molecular mobility, an integrated design derived from the orderly LC stacking and simultaneous crosslinking in various ratios of the dynamic 2(6-isocyanatohexylaminocarbonylamino)-6-methyl-4[1H]-pyrimidinone (UPy-NCO) and permanent hexamethylene diisocyanate (HMDI) along 1,4-olefins of Bd units offers necessary mechanical strength and molecular mobility, resulting in a series of dynamic LCNs (r-SBR-g-[M·HMDI·UPy]). LC textures, phase transitions, self-healing/welding, and shape memory capacities were comprehensively studied. All LCNs showed LC textures in POM around Tᵢ (42–53 °C), which definitely contributed to both mechanical performance and molecular mobility due to the 50 mol % orderly LC stacking. Ureidopyrimidinone (UPy) that forms a dynamic H-bond is beneficial for the temporary shape fixity ratio (Rf), recyclability, and self-healing/welding ability while decreasing the shape recovery ratio (Rᵣₑc) because UPy can increase breaking elongations but sacrifice the mechanical strength. However, HMDI that forms a covalent crosslink showed the contrary effect, as HMDI can effectively enhance the mechanical strength but reduce the chain mobility. It is evidenced that r-SBR45k-g-[M-0%, 2%] can hardly undergo shape recovery (Rᵣₑc = 0) despite Rf = 92.6%, while with regard to r-SBR45k-g-[M-10%, 2%], Rᵣₑc greatly increased to 100%, but Rf decreased to 46.2%. All LCNs showed a higher than 82% self-healing/welding efficiency, with an exception of r-SBR-g-[M-10%, 2%]. This indicated the cooperative effect of molecular compositions on the properties. The well-tailored construction of polymer chain architecture through quantitative synthesis proves to be a powerful strategy for manipulating properties.

Effect of process parameters and butadiene content on friction and wear behaviour of ABS components

Acrylonitrile butadiene styrene (ABS) is a widely used engineering polymer for various applications as it is of low cost and easily machined. The present work aims to study the effect of build orientation and butadiene content on the tribological properties of ABS parts made by Fused filament fabrication (FFF) process. Fabrication is done on Prusa cura I3 Bear upgrade machine considering the build orientation as the main parameter with two different grades of ABS. Specimens are fabricated with two different orientations, i.e., flat and on edge. Wear test is conducted on the prepared specimens using pin on disc tribometer. From the test results, it was found that ABS with 20% butadiene has a high wear rate compared to ABS with 30% butadiene. Maximum wear rate is observed on an on-edge prepared specimen with 20% butadiene at 20 N load, 200 rpm.

Role of butadiene content on tribological properties of polymeric components fabricated by FDM

Fused Deposition Modelling (FDM) is the most widely used additive manufacturing method to prepare 3dimensional parts made of polymers. Acrylonitrile butadiene styrene (ABS) is a thermoplastic polymer made of three monomers acrylonitrile, butadiene and styrene. ABS is of low cost and easily machined with better mechanical and chemical properties. The aim of the present work is to study the effect of butadiene content on the tribological properties of specimens made of ABS by FDM process. The specimens are prepared by considering the process parameter infill percentage (20%,50%,80%) with two different grades of ABS filaments on Prusa cura I3 Bear upgrade machine. Experiments are conducted on pin on disc apparatus to determine wear behaviour. The test results show that the butadiene content and infill density of the specimens affect the wear rate of ABS. Maximum wear rate is observed at 20% infill specimen containing 20% butadiene at 200 rpm 20 N load.

Copolymerization of norbornene and conjugated dienes using anilinonaphthoquinone-ligated nickel complexes

Copolymerization of norbornene (NB) with butadiene (BD) or isoprene (IP) was carried out using anilinonaphthoquinone-ligated nickel complexes with MMAO as a cocatalyst. The copolymerization of NB/BD showed higher activity than that of NB/IP. Increasing the ratio of diene in monomer feed decreased the copolymerization activity. Raising the polymerization temperature increased the activity and the molecular weight of the produced polymer but did not significantly affect the comonomer incorporation. The BD content was varied from 11 to 33 mol% with the number-average molecular weight (Mn) of 15000–60000 and the molecular weight distribution (Mw/Mn) of 1.3–1.6, while the IP content was varied from 15 to 41 mol% with Mn of 34000–83000 and Mw/Mn of 1.3–2.1. The glass transition temperatures of the copolymers determined by differential scanning calorimetry were 101–199 °C for the NB/BD copolymers and 97–205 °C for the NB/IP copolymers according to the diene content.

Temperature rising elution fractionation and fraction characterization of Trans-1, 4-poly(isoprene-co-butadiene)

In order to analyze the chain structure and sequence distribution of trans-1,4-poly(isoprene-co-butadiene) copolymers (TBIR) with different butadiene content, a preparative-temperature rising elution fractionation (P-TREF) technique was used to fractionate the TBIR into 10 to 12 fractions based on the elution temperature ranged from −40 °C to 70 °C. NMR, DSC and GPC were used to characterize the microstructure, butadiene incorporation, [BI], [II] and [BB] dyad sequence concentration, melting point, molecular weight and molecular weight distribution of the fractions. Two or multi-model GPC curves are observed for the lower temperature elution fractions and the molecular weight of the fractions shows an increased tendency with an increase in the elution temperature. The fractions obtained at −40 °C elution temperature are copolymers with short trans-1, 4-polyisoprene (TPI) blocks, high butadiene incorporation and lower melting temperature. The fractions obtained at 50 °C elution temperature are copolymers containing medium-length TPI blocks and short trans-1, 4-butadiene (TPB) blocks. The fractions obtained at the other elution temperatures are mainly copolymers with medium-length TPI blocks. The chain structure models of the TBIR fractions are proposed and possible formation mechanism is discussed.

On the β relaxations in poly(butadiene) and poly(styrene-butadiene) rubbers

The influence of the chemical microstructure on the secondary mechanical relaxations of PB and SBR has been studied by varying the content of vinyl, cis, trans butadiene and styrene groups. Two relaxational mechanisms are involved in their β mechanical relaxations with two distinct activation energies. The fitting by the summation of two Havriliak Negami functions of the experimental isochronal and isothermal curves prove that the vinyl groups are responsible for the contribution of the High Temperature part of the β-relaxation, whereas the butadiene 1,4 groups, cis and trans are at the origin of the low temperature part of this relaxation. Moreover, the intensity of the relaxation associated to each monomer appears to be proportional to their volume (and molar) fraction. Given the random characteristics of the studied copolymer, this suggests that the involved mechanisms are localized at the level of only one monomer unit.

Hips/zeolite hybrid composites as active packaging materials: Structure and functional properties

Desiccant composites were prepared from seven high impact polystyrene copolymers (HIPS) with different butadiene content and dispersed droplet size to study the effect of structure on their functional and application properties. A 4A type zeolite was used as desiccant. The thermodynamic analysis of structure development revealed that the embedding of the zeolite into the polybutadiene droplets is the thermodynamically favored process. Comparison of composite stiffness to theoretically predicted values indicated that considerable embedding occurs during composite preparation. The extent of embedding depends on zeolite content, but also on other factors like butadiene content and the droplet size of the elastomer. Composite stiffness and strength decreases with increasing extent of embedding, while functional properties are dominated by zeolite content. The initial rate of water adsorption increases, while overall rate decreases with increasing desiccant loading. Embedding influences only the initial rate of water adsorption which decreases slightly with increasing extent of encapsulation.

Influence of microstructure in nitrile polymer on curing characteristics and mechanical properties of carbon black-filled rubber composite for seal applications

Acrylonitrile butadiene rubber (NBR) is widely used in seal applications due to its excellent oil resistance. In this article, carbon black-filled NBR composites, which differed in their acrylonitrile (ACN) and butadiene content ratios, were prepared and their curing characteristics and mechanical properties were investigated. Curing characteristics were investigated by measuring chemical kinetics and onset temperature of cross-linking reaction. Cross-linking density was measured by the volume swelling test. Mechanical properties, oil resistance, and compression set (CS) tests were also conducted. From these results, it was found that the microstructure in NBR polymer is closely connected to the curing characteristics and mechanical properties of the composite. On increasing the ACN content, Shore A hardness, tensile strength at break, elongation at break, oil resistance, and CS were raised, while, on the other hand cross-linking density, kinetics of cross-linking reaction, and bound rubber content were decreased.

Styrene/Butadiene Rubber Prepared by Anionic Bulk Polymerization in a Twin‐Screw Extruder

ABSTRACTStyrene/butadiene rubber (SBR) was prepared by anionic polymerization using a twin screw extruder as the reactor. To study the relationship between microstructure and phase morphology, three SBRs were synthesized using different initiator complexes. With the addition of tetrahydrofuran (THF), the vinyl content of butadiene increased; the microstructure of SBRs was randomized, simultaneously. Transmission electron microscope and dynamic mechanical analysis showed that the compatibility of the two components became better with the increasing relative mass of the THF. The method used in this paper provides an environmentally friendly way to synthesize SBR, which is always synthesized through anionic solution polymerization.

Effect of butadiene/styrene ratio, block structure and carbon nanotube content on the mechanical and electrical properties of thermoplastic elastomers after UV ageing

Thermoplastic elastomers based on a triblock copolymer styrene-butadiene-styrene (SBS) with different butadiene/styrene ratios, block structure and carbon nanotube (CNT) content were submitted to accelerated weathering in a Xenontest, in order to evaluate their stability to UV ageing. It was concluded that ageing mainly depends on butadiene/styrene ratio and block structure, with radial block structures exhibiting faster ageing than linear block structures. Moreover, the presence of carbon nanotubes in the SBS copolymer slows down the ageing of the copolymer. The evaluation of the influence of ageing on the mechanical and electrical properties demonstrates that the mechanical degradation is higher for the C401 sample, which is the SBS sample with the largest butadiene content and a radial block structure. On the other hand, a copolymer derivative from SBS, the styrene-ethylene/butadiene-styrene (SEBS) sample, retains a maximum deformation of ∼1000% after 80 h of accelerated ageing. The hydrophobicity of the samples decreases with increasing ageing time, the effect being larger for the samples with higher butadiene content. It is also verified that cytotoxicity increases with increasing UV ageing, with the exception of SEBS, which remains non-cytotoxic up to 80 h of accelerated ageing time, demonstrating its potential for applications involving exposure to the environment.

Mechanical vs. electrical hysteresis of carbon nanotube/styrene–butadiene–styrene composites and their influence in the electromechanical response

Abstract The interesting properties of thermoplastics elastomers can be combined with carbon nanotubes (CNT) for the development of large strain piezoresistive composites for sensor applications. Piezoresistive properties of the composites depend on CNT content, with the gauge factor increasing for concentrations around the percolation threshold, mechanical and electrical hysteresis. The SBS copolymer composition (butadiene/styrene ratio) influences the mechanical and electrical hysteresis of composites and, therefore, the piezoresistive response. This work reports on the electrical and mechanical response of CNT/SBS composites with 4 wt% nanofiller content, due to the larger electromechanical response. C401 and C540 SBS copolymers with 80% and 60% butadiene content, respectively have been selected. The copolymer with larger amount of soft phase (C401) shows a rubber-like mechanical behavior, with mechanical hysteresis increasing linearly with strain until 100% strain. The copolymer with the larger amount of hard phase (C540) just shows rubber-like behavior for low strains. The piezoresistive sensibility is similar for both composites for low strains, with a GF ≈ 5 for 5% strain. The electrical hysteresis shows opposite behavior than the mechanical hysteresis, increasing with strain for both composites, but with higher increase for softer copolymer, C401. The GF increases with increasing strain, but this increase is larger for composites with lower amounts of soft phase due to the distinct initial modulus and deformation of the soft and hard phases of the copolymer. The soft phase shows larger strain under a given stress than the harder phase and the conductive pathway rearrangements in the composites are different for both phases, the harder copolymer (C540) showing higher piezoresistive sensibility, GF ≈ 18, for 20% strain.

Analytical method for determination of butadiene and styrene contents of styrene-butadiene rubber vulcanizates without pretreatment using pyrolysis-gas chromatography/mass spectrometry

Styrene-butadiene rubber (SBR) vulcanizates were prepared using various emulsion SBRs (ESBRs) and solution SBRs (SSBRs) with different microstructures, and were pyrolyzed without pretreatment. Principal pyrolysis products of SBR vulcanizates are butadiene and styrene. Butadiene and styrene contents of the SBR vulcanizates were determined using plots of the relative peak intensity ratio of butadiene/styrene as a function of the molar ratio of butadiene and styrene of the raw SBRs. The peak intensity ratio on the whole increased as the butadiene content increased. The correlation was enhanced by correction with the butadiene/styrene molar ratio of raw SBRs. For the plot of SSBR samples, the correlation was more enhanced by correction with the 1,2-unit/styrene molar ratio of raw SBRs. By using the corrected plots, butadiene and styrene contents of unknown SBR vulcanizates could be determined.

Extruded thermoplastic elastomers styrene–butadiene–styrene/carbon nanotubes composites for strain sensor applications

Tri-block copolymer styrene–butadiene–styrene (SBS) composites with different butadiene/styrene ratios and multi-walled carbon nanotubes (MWCNTs) can be used for the development of electro-mechanical sensors for large strains applications. Extruded CNT/SBS composites show percolation thresholds around 5wt%, electro-mechanical properties with high sensibility at larger strain and the gauge factor reach values up to 30 at strains of 20%. The butadiene/styrene ratio has influence in the mechanical and electro-mechanical properties. In one hand, the increase of the styrene content in copolymer increasing initial mechanical modulus, on the other hand, the increase of the butadiene content leads to larger maximum deformations and higher electro-mechanical sensibility for strains up to 20%. Further, applied initial pre-stress increases the electro-mechanical sensibility of the composites.

Molecular characterization of solution styrene-butadiene rubber: Thermal field-flow fractionation/multi-angle light scattering studies

Solution styrene-butadiene rubber (SSBR) is mainly constituted of a random copolymer of styrene and butadiene. SSBR usually contains microgels, having ultrahigh molecular weight (M>107g/mol), affecting rheological properties of the rubber. Thus, determinations of M and size distribution of these microgels are critical in performance evaluation and control for SSBR. We employ thermal field-flow fractionation (ThFFF), combined with online multi-angle light scattering (MALS), as most suited for characterization of solutions containing the microgels since they can be characterized in toto without removing the microgels from the solution. ThFFF-MALS was applied for characterization of linear and branched SBR materials from various commercial sources, and the results were compared to those from size-exclusion chromatography (SEC). ThFFF provides higher resolution than SEC for high molecular fractions and allowed gel content to be measured. The gel content was determined by subtracting the amount of sol from total injection mass, and was measured to be 10–15%. We infer from the characterization results that the microgel content may not be correlated to the microstructure, the styrene and vinyl content of butadiene but to the fraction of high molecular weight in SSBR. Finally, the macromolecular structure and the content of microgel (larger than about 100nm) were found to significantly affect various rheological parameters such as viscosity, mechanical and dynamic properties.

The microstructure and fracture performance of styrene–butadiene–methylmethacrylate block copolymer-modified epoxy polymers

The microstructure and fracture performance of an anhydride-cured epoxy polymer modified with two poly(styrene)-b-1,4-poly(butadiene)-b-poly(methyl methacrylate) (SBM) block copolymers were investigated in bulk form, and when used as the matrix material in carbon fibre reinforced composites. The ‘E21’ SBM block copolymer has a higher butadiene content and molecular weight than the ‘E41’. A network of aggregated spherical micelles was observed for the E21 SBM modified epoxy, which became increasingly interconnected as the SBM content was increased. A steady increase in the fracture energy was measured with increasing E21 content, from 96 to 511 J/m2 for 15 wt% of E21. Well-dispersed ‘raspberry’-like SBM particles, with a sphere-on-sphere morphology of a poly(styrene) core covered with poly(butadiene) particles, in an epoxy matrix were obtained for loadings up to 7.5 wt% of E41 SBM. This changed to a partially phase-inverted structure at higher E41 contents, accompanied by a significant jump in the measured fracture energy to 1032 J/m2 at 15 wt% of E41. The glass transition temperatures remained unchanged with the addition of SBM, indicating a complete phase separation. Electron microscopy and cross polarised transmission optical microscopy revealed localised shear band yielding, debonding and void growth as the main toughening mechanisms. Significant improvements in fracture energy were not observed in the fibre composites, indicating poor toughness transfer from the bulk to the composite. The fibre bridging observed for the unmodified epoxy matrix was reduced due to better fibre–matrix adhesion. The size of the crack tip deformation zone in the composites was restricted by the fibres, hence reducing the measured fracture energy compared to the bulk for the toughest matrix materials.

Effect of co-monomer ratio in ABS and wood content on processing and properties in wood/ABS composites

Acrylonitrile-Butadiene-Styrene copolymers (ABS) reinforced with wood flour were investigated for rheological, mechanical and thermal properties. Three grades of commercial ABS resin (high flow (HF-ABS), medium impact (MI-ABS) and super high impact (SI-ABS) grades) were characterized using H-NMR and elemental analysis for the determination of co-monomer content. Wood flour from Para rubber trees treated with N-2 (aminoethyl)-3-(aminopropyl) trimethoxy silane was blended with ABS in the melt blending process using a twin-screw extruder. Wood flour contents used in this work were 0.0 %, 9.1 %, and 33.3 % wt. The composites with higher acrylonitrile contents showed higher melt viscosity especially at the low shear rate. Carreau’s model was used for curve-fitting. The extrudate swell ratio of the composites tended to increase at the shear rate of 10–500 s−1 and then decreased dramatically once the shear rate were further applied. Neat ABS and wood/ABS composites with higher butadiene content illustrated a higher swelling ratio. The neat MI-ABS and composites showed the highest ultimate tensile strength and modulus due to the butadiene content effect. As the wood flour loading was increased, the tensile modulus of all ABS composites increased with the sacrifice of the tensile strength of composites. The elongation at break and impact strength were noticeably the highest for wood/SI-ABS composites among all because of the effect of rubbery butadiene content. Thermal stability of plastic in 9.1 % wood in HF-ABS composites was improved compared with the neat HF-ABS due to the low acrylonitrile content.

Preparation and characterization of acrylonitrile–butadiene–styrene/poly(vinyl acetate) membrane for CO 2 removal

CO 2 removal from different gas streams via the polymeric membranes has been propounded as an important issue in greenhouse gas emissions control, natural gas upgrading, and enhanced oil recovery. Here, polymeric blend membranes were prepared from acrylonitrile–butadiene–styrene (ABS) and poly vinyl acetate (PVAc), and their CO 2/N 2 and CO 2/CH 4 separation characteristics were investigated. The influence of different PVAc contents on gas separation performance and the effect of pressure, ranging from 1 to 8 bar, on CO 2 permeability were studied. Furthermore, the morphology of the membranes was analyzed by FTIR, XRD, DSC and SEM. It was shown that the highest CO 2 permeability of 5.72 Barrer for the membrane containing 10 wt.% PVAc, the highest CO 2/CH 4 selectivity was 29 in 20 wt.% PVAc and CO 2/N 2 was 40.41 in 30 wt.% PVAc contents. These results comprised from different effective factors such as PVAc acetate polar groups, compactness in polymer matrix at the presence of high molecular weight PVAc, and the acrylonitrile and flexible butadiene contents of ABS. Furthermore, in the transmembrane pressure of 2–8 bar the CO 2 permeability approximately descended with the pressure increase for PVAc content of 0–40 wt.%, and it ascended for 50–60 wt.%. Generally, the prepared membranes can be taken into account as better membranes for CO 2/N 2 separation than CO 2/CH 4.